PeytonM Posted December 23, 2019 Report Share Posted December 23, 2019 I’ve had the JPI 450 in my Mooney J for almost 20 years. The last few flights it’s been giving erratic read-outs of fuel flow, from 0 to over 200 GPH (!!), jumping wildly. I’ve attached a couple vids. Interestingly, during taxi and climb, it performs flawlessly! I’ve talked to JPI a couple times. Phone tech support said it was the transducer. “Just replace it.” (400 bucks.) I talked to them as Oshkosh; that guy suggested it was an electrical connection. He told me to check the connector at the transducer, in the fire sleeve. My mechanic pulled the fire sleeve and said there were no connectors, just wires running into the cabin. I’m still inclined to think it’s something in the wiring, but I have no idea where to start to look. The fact that it works during taxi & climb is baffling. Thank you in advance for you suggestions. A2EB932C-D77C-4600-AD0D-FF7CADD6CEFC.MOV F30C78BB-A41D-4D58-A114-EA0CE52C956F.MOV Quote Link to comment Share on other sites More sharing options...
ArtVandelay Posted December 23, 2019 Report Share Posted December 23, 2019 I would clean it using carburetor cleaner. Then retest.Tom 2 Quote Link to comment Share on other sites More sharing options...
Stephen Posted December 23, 2019 Report Share Posted December 23, 2019 Mine has been doing the same thing (EDM 900) fuel flow. If you are engaging JPI support, be sure to make sure you have a good ground to the engine from the system, that is the first thing JPI support seems to ask... Quote Link to comment Share on other sites More sharing options...
ArtVandelay Posted December 23, 2019 Report Share Posted December 23, 2019 Mine has been doing the same thing (EDM 900) fuel flow. If you are engaging JPI support, be sure to make sure you have a good ground to the engine from the system, that is the first thing JPI support seems to ask... I would expect other probes to show problems (CHT, EGT, etc) if there was a bad ground which is common to all.Tom Quote Link to comment Share on other sites More sharing options...
Stephen Posted December 23, 2019 Report Share Posted December 23, 2019 1 minute ago, ArtVandelay said: I would expect other probes to show problems (CHT, EGT, etc) if there was a bad ground which is common to all. Tom Yes agreed, i had same rational...they seem to always want that checked before moving on with troubleshooting though. I think it is their answer to "have you tried rebooting?" It may save you a support cycle if you validate it. Quote Link to comment Share on other sites More sharing options...
kortopates Posted December 23, 2019 Report Share Posted December 23, 2019 4 hours ago, PeytonM said: I’ve had the JPI 450 in my Mooney J for almost 20 years. The last few flights it’s been giving erratic read-outs of fuel flow, from 0 to over 200 GPH (!!), jumping wildly. I’ve attached a couple vids. Interestingly, during taxi and climb, it performs flawlessly! I’ve talked to JPI a couple times. Phone tech support said it was the transducer. “Just replace it.” (400 bucks.) I talked to them as Oshkosh; that guy suggested it was an electrical connection. He told me to check the connector at the transducer, in the fire sleeve. My mechanic pulled the fire sleeve and said there were no connectors, just wires running into the cabin. I’m still inclined to think it’s something in the wiring, but I have no idea where to start to look. The fact that it works during taxi & climb is baffling. Thank you in advance for you suggestions. A2EB932C-D77C-4600-AD0D-FF7CADD6CEFC.MOV F30C78BB-A41D-4D58-A114-EA0CE52C956F.MOV Its usually a bad connection. The wires on the transducer are not long enough to make it back into the cabin, so there are connectors or butt splices on the wires near the transducer. One of them is probably loose and affected by the faster airflow in cruise, but not affected in climb due to the steeper pitch and/or slower airspeed. 1 Quote Link to comment Share on other sites More sharing options...
jlunseth Posted December 23, 2019 Report Share Posted December 23, 2019 Went through the same thing with my 930. Had the fuel pump and fuel system rebuilt because the indication was it was an actual fuel flow issue. I like the new pump, but that was not the problem. It was the waterwheel, or as they are calling it, the transducer. Frankly, I would start by replacing the transducer. Quote Link to comment Share on other sites More sharing options...
Stephen Posted December 23, 2019 Report Share Posted December 23, 2019 I think Paul @kortopates may have a point with the airflow. I have exactly down to the taxi /climb-out operation, inop in cruise, works on decent/landing/taxi. I plan on checking the connections. From JPI's troubleshooting FAQ: Inaccurate/erratic fuel flow readings? September 05, 2012 by Craig Peyton 1.) Might have used sealant or Teflon tape on transducer threads. This can cause the transducer to fail. Do not use teflon tape, or thread sealant compound of any kind. [ See #503 Fuel Flow Installation Manual – Heading #2 “Initial Check Out” — line item #14.] 2.) Check that the transducer harness wiring is not routed with or adjacent to ignition wires, alternator wires, spark plug leads, or cabin heater ignition wires. Also check connections and crimps. 3.) Make sure there are no 90-degree fittings within 4” of the inlet/outlet side of the transducer. Cavitations in the transducer will result in inaccurate readings. 4.) Fuel Flow Tester available for $35.00 for testing instrument and transducer. Call the Sales Department at JPI at: 800-345-4574 Quote Link to comment Share on other sites More sharing options...
carusoam Posted December 24, 2019 Report Share Posted December 24, 2019 Consider the transducer, but.... 1) essentially they act like a water wheel with a magnet attached to the impeller... 2) outside of the sensor is a signal pick-up device that sends a voltage spike each time the magnet goes by... 3) The JPI will be counting the spikes and doing a calculation using the calibrated k-factor, and delivering a number in gph.... 4) If the water wheel gets dirty, it sticks... and the FF reading is usually lower than expected... 5) Getting a reading in the hundreds of gph... sounds more like noise... 6) sensors are pretty easy to remove and clean, blow some air gently through them... see if they are working... 7) Check all connections and wires... vibrations added to a loose connection can drive the count up pretty well.... 8) Also important... any fuel leaks seen? When the plane is idle... it may be leaking fuel. If it is leaking fuel while on the ground... it may be sucking air in flight....fuel foam going towards the engine shows up as high gph Numbers. Look for and report any blue fuel stains to your mechanic... Sensor costs are low enough, that spending hours testing it may not make enough sense... PP thoughts only, not a mechanic... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
Stephen Posted December 24, 2019 Report Share Posted December 24, 2019 5 hours ago, carusoam said: Consider the transducer, but.... 1) essentially they act like a water wheel with a magnet attached to the impeller... 2) outside of the sensor is a signal pick-up device that sends a voltage spike each time the magnet goes by... 3) The JPI will be counting the spikes and doing a calculation using the calibrated k-factor, and delivering a number in gph.... 4) If the water wheel gets dirty, it sticks... and the FF reading is usually lower than expected... 5) Getting a reading in the hundreds of gph... sounds more like noise... 6) sensors are pretty easy to remove and clean, blow some air gently through them... see if they are working... 7) Check all connections and wires... vibrations added to a loose connection can drive the count up pretty well.... 8) Also important... any fuel leaks seen? When the plane is idle... it may be leaking fuel. If it is leaking fuel while on the ground... it may be sucking air in flight....fuel foam going towards the engine shows up as high gph Numbers. Look for and report any blue fuel stains to your mechanic... Sensor costs are low enough, that spending hours testing it may not make enough sense... PP thoughts only, not a mechanic... Best regards, -a- Thanks @carusoam good synopsis. I do believe JPI says *not* to blow air through the transducer on their site, but I think that perhaps this is ok: but this is NOT ok: 2 Quote Link to comment Share on other sites More sharing options...
Stephen Posted December 24, 2019 Report Share Posted December 24, 2019 Yep, found it: https://www.jpinstruments.com/FAQ/do-not-blow-air-through-the-transducer/ 1 Quote Link to comment Share on other sites More sharing options...
carusoam Posted December 24, 2019 Report Share Posted December 24, 2019 Stephen, great resource find! Interesting... we have two threads in one day... One has FF in hundreds of gallons... The Other has FF at zero... Both are probably sensor related.... Not sure which one I would want to have to try and solve... Thanks for sharing the JPI resource.... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
PeytonM Posted December 24, 2019 Author Report Share Posted December 24, 2019 Thank you for all the suggestions. The fact that it’s worked for nearly 20 years leads me to the fuel transducer, and probably a connection. I like the hypothesis on airflow. That implicates the connection in question is in the engine compartment. I’ll investigate further. Thank you again....Merry Christmas & Happy Holidays! Quote Link to comment Share on other sites More sharing options...
Guest Posted December 25, 2019 Report Share Posted December 25, 2019 The rotor in a Floscan transducer spins on jewel bearing, likely the reason for not spinning them without liquid. From the Floscan website: Principal of Operation:Liquid enters the flow chamber tangentially, follows a helical flow path, and exits vertically, thereby venting any entrained vapor bubbles. The rotational velocity of the liquid is directly proportional to flow rate. A neutrally buoyant rotor spins with the liquid between V-jewel bearings. Rotor movement is sensed when notches in the rotor interrupt an infrared light beam between an LED and phototransistor.The vapor venting design requires that the transducer be positioned with the electrical connectors pointing up. Turbulence caused by valves or sharp elbows mounted close to the transducer inlet can affect transducer K-Factor and should be minimized. They should never be installed with sealing tape or non dissolving thread sealants which can block the fuel flow. Look up the lawsuit against Vans Aircraft for deaths caused by improper installation. Clarence Quote Link to comment Share on other sites More sharing options...
Stephen Posted December 26, 2019 Report Share Posted December 26, 2019 On 12/25/2019 at 8:49 AM, M20Doc said: They should never be installed with sealing tape or non dissolving thread sealants which can block the fuel flow. Look up the lawsuit against Vans Aircraft for deaths caused by improper installation. Clarence ================== I think EI FT-180 requires it with special attention to installation technique): From: https://iflyei.com/wp-content/uploads/0929031-FT-180-Info-Rev-D.pdf : "Teflon Tape and Pipe Dope (Thread Sealant):WARNING: The Inlet and Outlet ports are NPT threads. NPT threads are NOT self-sealing, thread sealant must be used. If thread sealant is not used, NPT threads WILL leak. If Teflon Tape is wrapped over the end of a male fitting, it will be sheared off during installation and can wrap itself around the flow transducer rotor or lodge itself in an orifice in the engine causing a dangerous fuel restriction. If Pipe Dope is placed in the female fitting or forward of the threads on the male fitting, it will dislodge and flow through the fuel system. It can attach itself to the flow transducer rotor or lodge itself in an orifice in the engine causing a dangerous fuel restriction." ================== JPI forbids it per https://www.jpinstruments.com/FAQ/fittings-used-on-the-transducer/ Quote Link to comment Share on other sites More sharing options...
Stephen Posted December 26, 2019 Report Share Posted December 26, 2019 For troubleshooting posterity, here is the the symptom: Notice JPI EDM 900 Fuel Flow erratic, but CHT/EGT / RPM/ MP/Engine Sound rock solid JPI900_Erratic_FuelFlow.mp4 Quote Link to comment Share on other sites More sharing options...
Guest Posted December 26, 2019 Report Share Posted December 26, 2019 1 hour ago, Stephen said: ================== I think EI FT-180 requires it with special attention to installation technique): From: https://iflyei.com/wp-content/uploads/0929031-FT-180-Info-Rev-D.pdf : "Teflon Tape and Pipe Dope (Thread Sealant):WARNING: The Inlet and Outlet ports are NPT threads. NPT threads are NOT self-sealing, thread sealant must be used. If thread sealant is not used, NPT threads WILL leak. If Teflon Tape is wrapped over the end of a male fitting, it will be sheared off during installation and can wrap itself around the flow transducer rotor or lodge itself in an orifice in the engine causing a dangerous fuel restriction. If Pipe Dope is placed in the female fitting or forward of the threads on the male fitting, it will dislodge and flow through the fuel system. It can attach itself to the flow transducer rotor or lodge itself in an orifice in the engine causing a dangerous fuel restriction." ================== JPI forbids it per https://www.jpinstruments.com/FAQ/fittings-used-on-the-transducer/ People are welcome to use whatever sealant they like. For me I won’t us Teflon tapes or sealants that won’t dissolve in 100LL. My guess is the Electronics International may not have experienced the pleasures of the US “justice” system yet. Clarence Quote Link to comment Share on other sites More sharing options...
Stephen Posted December 26, 2019 Report Share Posted December 26, 2019 2 hours ago, M20Doc said: People are welcome to use whatever sealant they like. For me I won’t us Teflon tapes or sealants that won’t dissolve in 100LL. My guess is the Electronics International may not have experienced the pleasures of the US “justice” system yet. Clarence I understand, but as an A & P installing the above EI, how do you not use sealant per the above guidance? Manufacturer says is WILL leak in all caps (with leaking 100 LL being an obvious danger and liability). Perhaps there may be some other clarifying guidance from EI... Interesting predicament. Maybe, the requirement for thread sealant is not an IE thing, maybe it is just that transducer, maybe there is newer or clarifying guidance. I could see comfort with the installation method being a consideration on which unit (IE vs JPI) to recommend to customers... Quote Link to comment Share on other sites More sharing options...
PT20J Posted December 26, 2019 Report Share Posted December 26, 2019 I've looked into the Floscan (now owned by JPI) transducers pretty extensively trying to improve the accuracy of the factory installation on my '94 J. Here are a few points I've learned. 1. The transducer is pretty simple and simply emits pulses as the fuel spins a plastic wheel. The K-factor is the number of pulses per gallon (usually around 29,000 calibrated at 16 gph). There are three wires which should be shielded: Ground, Power, Output. The output is an open collector transistor with pretty robust pulses. 2. Transducers can fail because the electronics die (no output), or the the wheel gets stuck (no output, intermittent output, reads low). One fix some have used to get a little more life out of a transducer is to soak it in Hoppes No. 9 or carburetor cleaner. I tried this on my intermittent unit and it worked better for a short while. I ended up replacing it. 3. Your symptom of flow rate sometimes reading unbelievably high seems strange because it is hard to see a way that the transducer could physically put out that many pulses. I'd talk to JPI again because maybe the 450 processor does something weird when it gets intermittent input. Since the transducer is that old, it might be worthwhile to replace it anyway. IIRC, the transducers are rated for 20,000 hours, but a tech from JPI told me that they frequently see them go bad after about 20 years. Or you could try soaking it. Probably not related to your problem, but just for completeness on the subject: 1. On M20J's, Mooney mounted the transducer upside down with a 45-degree ell at the input. I went to some trouble to remount it with the wires up and a straight fitting and it made no difference in accuracy. The only reason to mount it with the wires up is that the vent works properly in the unlikely event that you have vapor bubbles in the input line. 2. JPI recommends using steel fittings (the body is aluminum so aluminum fittings could gall -- especially if assembled dry). Mooney uses aluminum fittings, however. 3. Although JPI warns not to use sealant on the fittings, it's a bit of a crap shoot to get tapered pipe threads to seal without sealant because there is a spiral path around the threads and without sealant, the seal depends on deformation of the threads when tightening. But if you over tighten, it can crack the aluminum case. I couldn't get steel fittings to seal without sealant. If you apply a small amount of sealant to the male threads omitting the first two threads, you should be fine. 4. The Mooney factory K-factor setting on my Shadin miniflo-L did not match the installed transducer K-factor. After I replaced the intermittent transducer, I reset the K-factor in the Shadin to match the transducer K-factor and it was way off. I verified this by substituting a second known good miniflo-L. I reset the Shadin to the original Mooney K-factor and it is closer, but still not within 4%. I'm sure the transducers probably meet their spec of 2% accuracy at 16.0 gph, but I suspect they are less accurate at lower fuel flows and so some tweaking of the K-factor is probably required. Skip 1 Quote Link to comment Share on other sites More sharing options...
Guest Posted December 26, 2019 Report Share Posted December 26, 2019 2 hours ago, Stephen said: I understand, but as an A & P installing the above EI, how do you not use sealant per the above guidance? Manufacturer says is WILL leak in all caps (with leaking 100 LL being an obvious danger and liability). Perhaps there may be some other clarifying guidance from EI... Interesting predicament. Maybe, the requirement for thread sealant is not an IE thing, maybe it is just that transducer, maybe there is newer or clarifying guidance. I could see comfort with the installation method being a consideration on which unit (IE vs JPI) to recommend to customers... The AC43-13 says to not use Teflon tape on fuel system fittings. I don’t know how EI is going against FAA guidance? Clarence Quote Link to comment Share on other sites More sharing options...
Guest Posted December 26, 2019 Report Share Posted December 26, 2019 2 hours ago, bluehighwayflyer said: I fully support fellow Americans’ right to criticize our form of government, but even with the merits of their positions notwithstanding, I am strangely put off by the same from citizens of other countries. I have never heard any Canada bashing here. Would it be unreasonable, Clarence, to request the same from you as a citizen of our neighboring country to the north? Jim Most countries have the form of government that works best for them, if they don’t, they change them. I’m not suggesting anything about or bashing your government. There was a story recently in this forum where a law firm was trying to rent a Mooney to put on the court house lawn in an effort to bolster their case of defective magnetos that wouldn’t ignite water. This, and the Vans Aircraft suit I mentioned are examples of a “justice” system that many would agree does as much harm as it does good. I’m sorry if my comments offend you so much, I’ll try to do better. There is always the “ignore poster” function if it helps. Clarence Quote Link to comment Share on other sites More sharing options...
PT20J Posted December 27, 2019 Report Share Posted December 27, 2019 39 minutes ago, M20Doc said: The AC43-13 says to not use Teflon tape on fuel system fittings. I don’t know how EI is going against FAA guidance? Clarence Clarence, you got me curious since I recall Mooney installed the pipe fittings on my standby vacuum pump using teflon tape (which I believe the vacuum pump manufacturers caution against). According to this excerpt from the Service Manual, that's what Mooney says to use for all tapered pipe fittings. Personally, I think teflon tape is for plumbers not aircraft maintainers. I had a plumber doing some work at my home a while back and asked him what he used on tapered threads and he said, "Three wraps of teflon tape and pipe dope." I asked why he used both tape and dope and he said, "Because I don't want to come back." So, it appears that even plumbers don't trust teflon tape. Personally, I've had issues with it on gas and water pipes if the threads are not cut perfectly. I've come to prefer the dope for home plumbing jobs, and I don't think I'd use teflon tape on an airplane for fear that a shred might get loose and cause trouble. But, that's just me. Skip Quote Link to comment Share on other sites More sharing options...
Guest Posted December 27, 2019 Report Share Posted December 27, 2019 1 hour ago, PT20J said: Clarence, you got me curious since I recall Mooney installed the pipe fittings on my standby vacuum pump using teflon tape (which I believe the vacuum pump manufacturers caution against). According to this excerpt from the Service Manual, that's what Mooney says to use for all tapered pipe fittings. Personally, I think teflon tape is for plumbers not aircraft maintainers. I had a plumber doing some work at my home a while back and asked him what he used on tapered threads and he said, "Three wraps of teflon tape and pipe dope." I asked why he used both tape and dope and he said, "Because I don't want to come back." So, it appears that even plumbers don't trust teflon tape. Personally, I've had issues with it on gas and water pipes if the threads are not cut perfectly. I've come to prefer the dope for home plumbing jobs, and I don't think I'd use teflon tape on an airplane for fear that a shred might get loose and cause trouble. But, that's just me. Skip I was taught that Teflon tape has no place in aircraft other than in oxygen systems where oil based sealants can cause explosion or fire. Mooney says to use Parker Thread lube for fuel, hydraulic, oil and air fittings. Clarence Quote Link to comment Share on other sites More sharing options...
PT20J Posted December 27, 2019 Report Share Posted December 27, 2019 40 minutes ago, M20Doc said: I was taught that Teflon tape has no place in aircraft other than in oxygen systems where oil based sealants can cause explosion or fire. Mooney says to use Parker Thread lube for fuel, hydraulic, oil and air fittings. Clarence I interpreted that to mean the male threads on flare fittings since there is a separate paragraph for tapered thread fittings. But...I agree with you Quote Link to comment Share on other sites More sharing options...
markgrue Posted December 27, 2019 Report Share Posted December 27, 2019 3 hours ago, M20Doc said: The AC43-13 says to not use Teflon tape on fuel system fittings. I don’t know how EI is going against FAA guidance? Clarence I am fairly certain this is in regards to flare fittings. The flare fittings seal in the flare not the threads. Teflon tape would be useless in such a case. Mark 1 Quote Link to comment Share on other sites More sharing options...
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